When administering a fluid medicine or the like to a patient by intravenous injection using an indwelling vascular catheter, an indwelling needle, or the like, tension that acts on an infusion tube due to body motion of the patient may cause a tip opening of the indwelling catheter or the indwelling needle to remain in subcutaneous tissue in a state where the tip opening is dislodged from a blood vessel and may result in the fluid medicine leaking into surrounding subcutaneous tissue.
Depending on ingredients of a fluid medicine, leakage of the fluid medicine into surrounding subcutaneous tissue may cause inflammation accompanied by pain in the surrounding subcutaneous tissue and, in extreme cases, may result in necrosis of the tissue. Therefore, it is necessary to detect leakage of the fluid medicine at an early stage and promptly perform treatment involving neutralization and suction of the leaked drug and the use of an anti-inflammatory agent or the like.
In consideration thereof, various types of leakage detecting apparatuses for detecting leakage of a fluid medicine during intravenous injection have been proposed.
Patent Document 1 discloses a method of measuring swelling due to leakage using a change in optical path lengths by sequentially transmitting optical pulse signals (infrared rays) to a skin surface into which an injection needle is inserted and measuring arrival times of optical pulse signals reflected inside a human body.
Patent Document 2 discloses a method which utilizes a principle that a fluid medicine accumulated under the skin due to leakage absorbs microwave and causes the microwave to attenuate, and which checks for leakage based on attenuation by irradiating microwave to an intravenous injection site and measuring the magnitude of reflected waves.